main.dart

import 'package:flutter/material.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: MyHomePage(),
    );
  }
}

class MyHomePage extends StatefulWidget {
  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  int _counter = 0;
  List<String> homePageList = List();

  void _incrementCounter() {
    setState(() {
      _counter++;
      homePageList.add('A' + _counter.toString());
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Flutter Demo Home Page'),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            Text(
              'homePageList',
            ),
            Text(
              '$homePageList',
              style: Theme.of(context).textTheme.display1,
            ),
            FlatButton(
              color: Colors.blue,
              child: Text('Next Screen'),
              onPressed: () {
                Navigator.push(
                  context,
                  MaterialPageRoute(
                    builder: (context) => OtherScreen(
                      passedInList: homePageList,
                    ),
                  ),
                );
              },
            )
          ],
        ),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: _incrementCounter,
        tooltip: 'Increment',
        child: Icon(Icons.add),
      ),
    );
  }
}

class OtherScreen extends StatefulWidget {
  OtherScreen({Key key, this.passedInList}) : super(key: key);

  final List<String> passedInList;

  @override
  _OtherScreenState createState() => _OtherScreenState();
}

class _OtherScreenState extends State<OtherScreen> {
  List<String> _otherScreenList;

  @override
  void initState() {
    super.initState();

    _otherScreenList = List<String>.from(widget.passedInList);
  }

  void _removeLast() {
    setState(() {
      // only remove from _otherScreenList, but it still removes from the widget.passedInList
      _otherScreenList.removeLast();
      print('widget.passedInList: ' + widget.passedInList.toString());
      print('_otherScreenList: ' + _otherScreenList.toString());
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Other Screen'),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            Text(
              'widget.passedInList',
            ),
            Text(
              '${widget.passedInList}',
              style: Theme.of(context).textTheme.display1,
            ),
            Text(
              'otherScreenList',
            ),
            Text(
              '$_otherScreenList',
              style: Theme.of(context).textTheme.display1,
            ),
          ],
        ),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: _removeLast,
        tooltip: 'Remove last',
        child: Icon(Icons.minimize),
      ),
    );
  }
}